Comunicação Óptica, Fotônica em Silício, PIC, MZM, Junção PN, Fabricação, Variações Geométricas, FOM, BER.
Name: FELIPE ANTONIO MOREIRA SILVA
Publication date: 08/06/2026
Examining board:
Name |
Role |
|---|---|
| MARCELO EDUARDO VIEIRA SEGATTO | Presidente |
| MARIA JOSE PONTES | Examinador Interno |
| PABLO RAFAEL NEVES MARCIANO | Coorientador |
| REGINALDO BARBOSA NUNES | Examinador Externo |
Summary: The exponential growth of data traffic imposes increasingly stringent requirements on optical systems, particularly in terms of energy efficiency, bandwidth, and scalability, consolidating silicon photonics as a strategic platform for the development of photonic integrated circuits (PICs). In this context, the standardization of process design kits (PDKs) and fundamental
building blocks, such as optical modulators, becomes essential to ensure performance predictabil-ity and fabrication robustness. Among these core devices, the PN-junction-based integrated Mach–Zehnder modulator (MZM) stands out due to its CMOS compatibility and wide appli-cation in high-speed optical communication systems. This dissertation presents a case study aimed at mapping and quantifying the impact of fabrication-induced geometric variations on the performance of a silicon-based MZM, considering deviations in waveguide width and height.
The main figures of merit were extracted and correlated, including optical losses, insertion loss, electro-optic bandwidth, optical modulation amplitude, modulation losses, as well as system-level metrics such as eye diagram performance and bit error rate (BER). The results revealed a direct trade-off between modulation efficiency and optical losses, with insertion loss varying from 7.4 dB to 20.7 dB, in addition to bandwidth variations associated with the RC product and the
velocity mismatch between optical and electrical waves. At the system level, for operation at 1550 nm and a data rate of 20 Gbit/s using NRZ modulation, both back-to-back (B2B) and transmission links up to 100 km of single-mode fiber were evaluated, demonstrating that small dimensional variations can significantly degrade performance, with BER ranging from 1036 under ideal conditions to values between 0.1 and 0.2 in less robust configurations. As a main contribution, this work systematically quantifies the sensitivity of the modulator to geometric tolerances, establishing direct relationships between dimensional deviations and the degradation of electrical, optical, and system-level metrics, thereby providing guidelines for more robust device design and for the incorporation of tolerance margins into silicon photonics PDKs.
